The present invention relates to mixing valve. More particularly this invention concerns a control knob for a thermostatically controlled mixing valve.
A standard thermostatically regulated valve such as described in German patent 3,530,812 filed 29 Aug. 1985 by J. Kostorz has hot- and cold-water inlets connected to respective valve seats whose other sides open into an outlet compartment from which tempered water flows. A double valve body is displaceable in one direction to increase the flow from one of the inlets to the outlet compartment and decrease the flow from the other compartments and is oppositely movable for the opposite effect. This valve body can be moved by axially displacing an externally displaceable stem, and is also provided with a temperature-sensitive element in the outlet compartment that can change length to move the valve element and keep it at the setting it is originally put into. Thus once a given mixed-water temperature is set, the temperature-sensitive element will automatically move the valve bodies in response, for instance, to varying supply temperatures to keep the output temperature steady.
Commonly owned U.S. Pat. No. 5,242,108 describes a control assembly for a thermostatically regulated mixing valve having a housing and a stem extending along an axis in the housing and axially displaceable to adjust the thermostatically regulated temperature of the valve. The assembly has a control knob that has a nut threaded on the housing, axially linked to the valve stem, and rotatable about the axis in one direction to move axially inward and move the stem axially inward and in the opposite direction to move axially outward and move the stem axially outward. An inner knob part formed with an angularly extending and axially throughgoing slot is axially coupled to the housing and rotationally coupled to the nut so that the inner knob part rotates with the nut but does not move axially therewith. A stop fixed relative to the housing offset from the axis is angularly engageable with an abutment carried on an outer knob part, projecting through the slot, and displaceable between a normal position angularly engageable with the stop and a displaced position angularly out of alignment with the stop. Formations releasably secure the outer knob part on the inner knob part in any of a plurality of angularly offset positions relative to each other.
Thus with this system the knob does not move axially on the housing as the temperature is adjusted as is desired in modern-day plumbing fittings. The temperature range is normally limited to a maximum temperature which can be overridden easily by pushing the abutment into the displaced position. The maximum normal temperature can easily be changed by decoupling the outer knob part from the inner knob part, changing its angular position somewhat, and then reinstalling it.
It is therefore an object of the present invention to provide an improved actuating system for a thermostatic mixing valve.
Another object is the provision of such an improved actuating system for a thermostatic mixing valve. which overcomes the above-given disadvantages, that is which is of simpler and more rugged design than the prior-art systems and that has more adjustment capacity.
A thermostatically regulated mixing valve has a housing and a stem extending along an axis in the housing and axially displaceable to adjust the thermostatically regulated temperature of the valve. According to the invention a tubular core body fixed in the housing and aligned with the stem holds a coupling body axially displaceable in the core body, having an inner end axially engageable with the stem and an outer end formed with a screwthread. Interengaging formations on the coupling body and the core body inhibit rotation of the coupling body in the core body while permitting axial displacement of the coupling body in the core body. A knob rotatable about the axis has a screwthread meshing with the screwthread of the coupling-body outer end. A retainer engaged between the knob and the core body inhibits axial displacement of the knob on the core body and permits rotation of the knob on the core body so that rotation of the knob on the core body axially shifts the coupling body in the core body.
Such construction is extremely rugged, yet simple to manufacture and assemble. It can be counted on to have a long service life.
The coupling body in accordance with the invention has a pair of axially relatively displaceable parts and a spring urging them apart so that the coupling body acts as a force limiter. The knob has a radially outwardly projecting rim and the retainer includes a retaining element having a radially inwardly projecting rim bearing axially on the outwardly projecting rim and retaining it against the coupling body. A slide washer is engaged axially between the rims and the coupling body.
The retaining element according to the invention and the coupling body are formed with complementary axially interengageable arrays of radially projecting and axially extending teeth so that the retaining element can be fitted in an of a multiplicity of angularly offset positions on the coupling body. This provides a wide range of adjustability. The retainer includes a clip engaged transversely of the axis between the retaining element and the coupling body.
The coupling formations include a polygonal-section part on the coupling body and a complementary polygonal-section bore in the core body in which the coupling body is axially shiftable but nonrotatable. In addition the coupling body has a cylindrical inner surface and the core body has a cylindrical outer surface fitting snugly in the coupling body inner surface. This ensures solid mounting of the knob so it turns smoothly. Furthermore according to the invention at least one slide/friction ring is provided between the surfaces. Thus the vibration of normal use will not be enough for the knob to shift position.
The knob according to the invention has an inner lining part fitted to the coupling body and having an array of radially outwardly projecting and axially extending teeth, an outer decorative part having an array of radially inwardly projecting and axially extending teeth fitting with the inner-part teeth, and a screw for fixing the knob parts releasably together.